is jujutsu kaisen episode 20 filler?

Gojo arrives and ends the invasion. Hanami retreats before the strongest sorcerer can engage fully.

The students survive, but the victory feels hollow — the attack was a diversion, and Mahito's schemes advanced while everyone was focused on the event. Gojo's effortless handling of the situation reinforces both his power and the danger of the plans being built specifically to remove him from the board.